The present invention relates to caster assemblies and more particularly to the type of caster having a swivel plate mounted on the upper surface of a wheel carrying horn member. Casters of this type are used extensively in heavier load applications such as supporting work dollies, pallets and scaffolding equipment. In heavier load applications an axial thrust bearing, such as a ballbearing assembly, is provided between the swivel plate and the upper surface of the horn to reduce the frictional resistance to swivelling motion and to distribute the load evenly to the horn from the supported equipment. It is desirable that these bearings be adequately lubricated during the life of the caster and toward this end, a nipple-type metal lubrication fitting is frequently provided on the underside of the horn along with a seal in the space between the swivel plate and the horn member to prevent excessive lubricant escape.
The disadvantage in this prior lubrication arrangement, in addition to its high cost of manufacture, is that it is necessary to turn the entire article supported on the casters over to obtain access to the lubrication fitting with a conventional pressurized lubricant valve or gun.
It is a primary object of the present invention to ameliorate the problems described above in swivel plate type casters having pressurized bearing lubrication.